Protractor



W. D. WEBBER Oct. 4, 1955 PROTRACTOR 2 Sheets-Sheet l @ZM T m W@ Oct. 4,1955 w. D. WEBBER 2,719,359

PROTRACTOR Filed Oct. 15, 1954 2 Sheets-Sheet 2 I N VEN TGR.

ATTD RN EYE United States Patent C PROTRACTOR William D. Webber,Chicago, Ill.

Application October 15, 1954, Serial No. 462,553

8 Claims. (Cl. 33-1) This invention relates to a measuring instrument,and more particularly to a protractor.

This invention is an improvement over the protractor shown and describedin my Patent No. 2,602,228.

The object of the invention is to provide a yprotractor which willenable the user to not only accurately determine any angle of anydegree, but also to conveniently determine any fractional part of adegree.

Another object of the invention is to provide a protractor which can beused to determine any degree and any fractional part of a degree down tothe minute and wherein an angle can be determined even from a course thebearings of which are unknown.

A further object of lthe invention is to lprovide a protractor which isextremely simple and inexpensive to manufacture.

Other objects and advantages will be apparent during the course of thefollowing description.

ln the accompanying drawings, forming a part of this application, and inwhich like numerals are used to designate like parts throughout thesame:

Figure l is a top plan View of the protractor, constructed according7 tothe present invention, and with parts broken away and in section.

Figure 2 is a cross sectional View taken through the protractor ofFigure 1.

Figure 3 is a fragmentary plan view yof the base.

Figure 4 is an enlarged fragmentary sectional view showing certainconstructional details of the protractor.

Figure 5 is a sectional view showing the relationship between the base,disc'and ring.

Figure 6 is a plan view of a modified protractor, with parts broken awayand in section.

Figure 7 is a cross sectional view taken through the protractor ofFigure 6, and with the parts disassembled.

Figure 8 is a cross sectional View taken through the protractor ofFigure 6, and showing the parts in their assembled position.

Figure 9 is a fragmentary sectional View showing a modified protractorwherein a thumb screw is used for maintaining the parts immobile intheir adjusted positions.

Referring in detail to the drawings, the numeral 10 designates a ringwhich can be made of any suitable material such as a transparentplastic, and the lower surface of the ring 1t) is provided with acircular recess or cutout i1. Snugly seated in the recess 11 is acircular base 12 which is also made of transparent material, androtatably connected to the base 12 is a circular disc 14.

A suitable securing element such as a rivet 15 serves to rotatablyconnect the disc 14 and base 12 together, Figures 2 and 4. The disc 14is provided with a plurality of large cutouts or openings 16 which areadapted to register with openings 17 in the base 12. These openings 16and 17 are adapted to be engaged by the users fingers when theprotraetor is to be lifted up olf of a at surface. The straight edges ofthe large cutouts 16 and 17 which parallel the sides of the table 32 arebeveled or tapered on 23,719,359 Patented Oct. 4,l 1955 the disc 14 andon the base 12, as indicated by broken lines in Figure 1. The outerperiph/:ry of the ring 10 is beveled or tapered as at 18 whereby theouter periphery of the ring 10 terminates in a sharp edge for increasingthe accuracy with which the protractor can be read or used. The ring 10is provided with a circular cutout or opening 20 in which is rotatablymounted the inner disc 14. The inner edge of the ring 10 is beveled ortapered as at 19, Figure 5, and the adjacent outer edge of the disc 14is also beveled or tapered as at 21. Thus, it will be seen that thesetapered surfaces 19 and 21 cooperate whereby with the parts assembled asshown in Figure 2, the ring 10 is prevented from accidentally moving outof its proper position.

The base 12 is divided into four quadrants 22, and two of thesequadrants have scales or graduations thereon, these graduations beingindicated by the numeral 23, Figures l and 3, The ring 10 is alsodivided into four quadrants of degrees each and the dividing lines ofthe quadrants on the ring 10 are at the points indicated by the numerals24, 25, 26 and 27. The ring 10 is further provided with four rows orsets of graduations or markings on one half thereof, and these four rowsof scales or markings are designated by the numerals 28, 29, 30 and 31,Figure l. A reference table 32 may be imprinted on the disc 14 orarranged thereon in any suitable manner.

Referring to Figures 6, 7 and 8 of the drawing there is shown a modifiedprotractor wherein the numeral 33 designates a ring which can be made ofa transparent material. The lower surface of the ring 33 is providedwith a recess 40, and the ring 33 is provided with cutouts 34 whichdefine a rib or crossbar 35. The crossbar 35 has an opening 36 throughwhich is adapted to be projected a suitable securing element such as arivet 37, and the rivet 37 also extends through a registering opening 38in a base 39. The base 39 is snugly and rotatably seated in the recess40 in the lower surface of the `ring 33. After the rivet 37 has beeninserted through the openings 38 and 36, it may be peened over as shownin Figure 8 so as to maintain the ring 33 and base 39 connectedtogether.

The base 39 may have on its upper surface the reference table 32, andthe base 39 is divided into four quadrants 22 in the same manner as thepreviously described base 12. Also, two of the quadrants 22 havegraduations 23 thereon. Also, the ring 33 is divided into four quadrantsand the dividing lines between the four quadrants on the ring 33 areagain indicated by the numerals 24, 25, 26 and 27. Furthermore, the ring33 has the four sets of markings or graduations 28, 29, 30 and 31 asdoes the previously described ring 10.

Referring to Figure 9 of the drawing, there is shown a furthermodification wherein instead of using the rivet 37, a screw 41 may beextended through the openings 38 and 36 for maintaining the partsconnected together. A nut 42 is arranged in threaded engagement with thescrew 41, so that by tightening the nut 42 on the screw 41, the ring 33and base 39 can be maintained immobile with respect to each other afterthey have been adjusted to a desired position.

From the foregoing it is apparent that there has been provided aprotractor which is an improvement over the protractor shown anddescribed in my Patent No. 2,602,228. The precision instrument of thepresent invention will permit the user to not only determine an angle ofany degree but will also permit the user to conveniently determine anyfractional part of a degree. The instrument is simple to make, accurateto use, easy to operate and inexpensive to manufacture. The instrumentshown in Figures l through 5 is composed of three main parts that is thering 10, base 12 and disc 14. The ring 10 can be rotated and is held inplace by means of the interengaging surfaces 21 and 19. However, thedisc 14 and base 12 can be laminated together or else they can berigidly connected together by means of the eyelet or rivet 15.

The graduations 23 on the base 12 are computed by dividing seventy-sixdegrees (76) into fifteen (15) equal parts. The graduations on the base12 are thus spaced five degrees and four minutes (05 04') apart. Thesegraduations read from Zero to the right and to the left and are asfollows: Five degrees and four minutes 04'); ten degrees and eightminutes (10 08'); lifteen degrees and twelve minutes (15 12'); twentydegrees and sixteen minutes 16'); twenty-five degrees and twenty minutes20'); thirty degrees and twentyfour minutes 24'); thirty-five degreesand twentyeight minutes 28'); forty degrees and thirty-two minutes 32');forty-five degrees and thirty-six minutes 36'); fifty degrees and fortyminutes (50 40'); fifty-five degrees and forty-four minutes 44'); sixtydegrees and forty-eight minutes 48'); sixty-five degrees and fifty-twominutes 52'); seventy degrees and fifty-six minutes 56'); andseventy-five degrees and sixty minutes 60').

The graduations 28, 29, 30 and 31 on the ring 10 or on the ring 33 arein degrees. Thus, by rotating the ring 10, in either direction for anygiven number of degrees, the degree graduations on the ring 10 willalways be relatively in the same location in relation to the graduationson the base 12. It follows therefore that if the ring 10 or the ring 33is moved to the desired number of degrees, and an additional fractionalpart of a degree is desired, the ring 10 can be moved in the samedirection until the degree graduation on the ring 10 near the desiredminute graduation 23 on the base 12 is registered thereon. Therefore,with a protractor of this type, it is posible to not only determine anydesired degree, but in addition, to determine any fractional part of adegree to the extent of four minutes (04') or any multiple thereof.

The ring and base are each divided into four quadrants of ninety degreeseach. The dividing lines between the quadrants on the rings are at thepoints 24, 25, 26 and 27. On each side of these points on the ring 10,there are graduations which are spaced fifteen minutes (15') apart, viz:Fifteen minutes 15'); thirty minutes (30'), and forty-five minutes(45'), for convenience in determining any of those fractional parts of adegree.

Due to the fact that the protractor can be made of any practical size,the combination of the degrees on the ring 10 and the fractional partsof the degrees on the base 12 plus the fifteen minute 15') graduationsat points 24, 25, 26 and 27, on the ring 10 make it possible for theuser of the protractor to determine any degree and any fractional part0f a degree down to the minute, as evidenced by the reference table 32.The table 32 is included on the protractor as a ready reference.

The openings 16 and 17 which register with each other facilitate thepicking up and handling of the protractor.

In Figures 6 through 9, there is shown a protractor which is used in thesame manner as the previously described protractor of Figures l through5. However, in Figures 6 through 9 the rotary wheel or ring 33 has acrossbar 35 which extends through its center and is an integral partthereof. The crossbar 35 is pivotally connected to the base 39 by meansof a shaft or rivet 37. As shown in Figure 9 a thumb screw 41 and nut 42can be used to lock the ring 33 in any desired angular position whendesired.

The protractors of the present invention are made of transparentmaterial such as of suitable plastic. With the present invention anyangle can be determined even from a course the bearings of which areunknown. Thus, courses do not always have reference to compass bearingsand it is not always necessary to have the point zero of the protractorset at true north. Courses are not always necessarily described bycompass bearings in relation to magnetic north or true north. Angles canbe determined from courses without relation to compass bearings and thepresent invention goes beyond the scope of the prior art in that notonly any degree but any fractional part thereof can be determined. Also,the protractor can be used without reference to compass bearings.

The table 32 is used for the purpose of eliminating the necessity ofmentally calculating any fractional part of a degree when it is otherthan four minutes (04') or a multiple thereof. The following is anexample: assuming that an angle of ten degrees and thirty-three minutes(10 33') to the right is desired. See the table 32 which shows 33(48-15). Then, move the ring 10 to the right ten degrees (10), and thenmove ring 10 in the same direction until the degree graduation on thering 10 near the forty-eight minute (48') graduation on base 12 isregistered thereon. By marking the point of angle at the fifteen minute(15') graduation directly to the left of 26 on ring 10, it will be theangle desired because, as indicated in the table 32, in order todetermine said fractional part of a degree it is necessary to first addforty-eight minutes (48'), and then subtract fifteen minutes (15')therefrom, as the table 32 shows.

The graduations indicated by the numeral 23 on the base 12 of Figure land on the base 39 of Figure 6 are adapted to be engraved on the uppersurface of the base and can preferably be in red, whereas the degreegraduations and the fifteen minute (15') graduations on the ring 10 ofFigure 1 and on the ring 33 of Figure 6 are to be in black so that thegraduations on the ring will readily be distinguishable from thegraduations on the base. The dividing lines between the quadrantsindicated by the numerals 24, 25, 26 and 27 are indicated by the numeral13 on the base 12 of Figure l, and these dividing lines are indicated onthe base 39 of Figure 6 by the lines 43. The dividing lines 13 or 43 areadapted to be engraved on the lower surface of the base, but on theupper surface thereof at the points directly under the degreegraduations on the ring 10 of Figure l, or the ring 33 of Figure 6.Furthermore, the degree graduations and the fifteen minute (15')graduations on the ring 10 of Figure 1 and on the ring 33 of Figure 6are engraved on the lower surface thereof. The purpose of this is to beable to secure exact registrations and readings when using theprotractor.

For a further clarification to show how various angles are determined:Moving the ring 10, for example counterclockwise, to a point making anangle of thirty-two degrees and twenty-four minutes (32 24') at thepoint indicated by the numeral 26 on the ring 10, the other angles wouldbe: one hundred twenty-two degrees and twentyfour minutes (122 24') atthe point indicated by the numeral 25 on the ring 10; two hundred twelvedegrees and twenty-four minutes (212 24') at the point indicated by thenumeral 24 on the ring 10; and, three hundred two degrees andtwenty-four minutes (302 24') at the point indicated by the numeral 27on the ring 10.

I claim:

1. In a protractor, a circular base divided into quadrants, two of saidadjacent quadrants each having seventysix degree (76) graduations spacedfive degrees and four minutes (05 04') apart, a ring provided with acircular recess in its lower surface rotatably receiving said base, saidring being divided into quadrants, two of the adjacent quadrants of saidring being graduated in degrees, the outer periphery of said ring beingtapered to a sharp edge and having graduations arranged at the dividinglines between the quadrants on the ring, said last named graduationsbeing spaced fifteen minutes 15') apart, a disc arranged within saidring and connected to said base, the contiguous edges of said disc andring being inclined and engaging each other.

2. In a protractor, a circular base divided into quadrants, two of saidadjacent quadrants each having seventysix degree (76) graduations spacedlive degrees and four minutes (05 04') apart, a ring provided with acircular recess in its lower surface rotatably receiving said base, saidring being divided into quadrants, two of the adjacent quadrants of saidring being graduated in degrees, the outer periphery of said ring beingtapered to a sharp edge and having graduations arranged at the dividinglines between the quadrants on the ring, said last named graduationsbeing spaced fifteen minutes (15') apart, a disc arranged within saidring and connected to said base, the contiguous edges of said disc andring being inclined and engaging each other, there being registeringopenings in said disc and base for the projection therethrough of theusers fingers,

3. In a protractor, a circular base divided into quadrants, two of saidadjacent quadrants each having seventysix degree (76) graduaions spacedfive degrees and four minutes (05 04') apart, a ring provided with acircular recess in its lower surface rotatably receiving said base, saidring being divided into quadrants, two of the adjacent quadrants of saidring being graduated in degrees, the outer periphery of said ring beingtapered to a sharp edge and having graduations arranged at the dividinglines between the quadrants on the ring, said last named graduationsbeing spaced fifteen minutes (15') apart, a disc arranged within saidring and connected to said base, the contiguous edges of said disc andring being inclined and engaging each other, there being registeringopenings in said disc and base for the projection therethrough of theusers fingers, said base, ring and disc being made of transparentmaterial.

4. A protractor comprising a ring provided with a circular recess in itslower surface, a base seated in said recess, the inner portion of saidring being cutout to define a crossbar, means rotatably connecting saidbase to said crossbar, said base being divided into quadrants, two ofsaid adjacent quadrants on the base each having seventy-six degree (76)graduations spaced five degrees and four minutes (05 04') apart, saidring being divided into quadrants, two of the adjacent quadrants of thering being graduated in degrees, the outer periphery of said ring beingtapered to a sharp edge and having graduations arranged at the dividinglines between the quadrants on the ring, said last named graduationsbeing spaced fifteen minutes (15') apart.

5. A protractor as defined in claim 4, wherein said means comprises asecuring element extending through said base and crossbar,

6. A protractor as defined in claim 4, wherein said means comprises athumb screw extending through said base and crossbar, and a nut arrangedin engagement with said thumb screw.

7. A protractor comprising a ring provided with a circular recess in itslower surface, a base seated in said recess, means rotatably connectingsaid base to said ring, said base being divided into quadrants, two ofsaid adjacent quadrants each having seventy-six degree (76) graduationsthereon spaced five degrees and four minutes (05 04') apart, said ringbeing divided into quadrants, two of the adjacent quadrants of said ringbeing graduated in degrees, the outer periphery of said ring beingtapered to a sharp edge and having graduations arranged at the dividinglines between the quadrants on the ring, said last named graduationsbeing spaced fifteen minutes (15') apart.

8. In a protractor, a circular base divided into quadrants, two of saidadjacent quadrants each having seventysix degree (76) graduations spacedfive degrees and four minutes (05 04') apart, a ring provided with acircular recess in its lower surface rotatably receiving said base, saidring being divided into quadrants, two of the adjacent quadrants of saidring being graduated in degrees, the outer periphery of said ring beingtapered to a sharp edge and having graduations arranged at the dividinglines between the quadrants on the ring, said last named graduationsbeing spaced fifteen minutes (15') apart, a disc arranged within saidring and connected to said base, the contiguous edges of said disc andring being inclined and engaging each other, and a table on saidprotractor for eliminating the necessity of mentally calculating anyfractional part of a degree when it is other than four minutes (04') ora multiple thereof.

No references cited.

